The invention relates generally to video data processing and more particularly to a method and apparatus for enhanced encoding of video signals.
Encoding analog video signals in digital format has presented a new array of features for users. One such feature is the ability to record large amounts of the digital video stream in a reasonable amount of digital storage space such that the capabilities of a traditional videocassette recorder (VCR) can be realized on a home computer. Such an application is often referred to as a digital VCR, digital video recorder (DVR), or personal video recorder (PVR). In operation, these systems typically encode the video data into an MPEG format prior to storage in the storage media, as the MPEG format provides some level of compression of the video information.
A drawback of these systems is that any information included in the vertical blanking interval (VBI) is not preserved through the encoding process. The VBI is a portion of the analog video signal corresponding to the time during which portion of the screen that is being drawn to returns from the bottom of the screen to the top. No video display information is required during this time interval, and it is often employed to carry additional data related to the video signal such as closed caption data, parental control information, etc. Because the encoding process does not preserve VBI data, closed caption and other VBI data included in the video data stream is lost and cannot be recovered from the stored encoded video stream.
Another limitation of digital VCRs, or other systems that store portions of video data streams for later use is the lack of support for copy protection standards. Typically, when the video stream is encoded, any copy protection information included in the video data stream is lost. Thus, if a user is able to store the video data stream in an encoded format on a storage media and retrieve it later for use, the copy protection included in the original video signal has effectively been defeated.
Therefore, a need exists for a method and apparatus for encoding a video data stream that supports information included in the vertical blanking interval and also supports copy protection that may be included in the received video signal such that unauthorized use of the signal is not possible.